In general, boilers used for heating rooms or halls are classified into an oil boiler, a gas boiler, and an electric boiler according to kinds of fuel supplied to the boilers. The boilers have been variously developed and used corresponding to a size of a room or a hall desired by a user or their installation purpose. Among such boilers, it is very important for the gas boiler to maintain a normal combustion state by controlling an amount of air according to temperature variation of ambient air such that a predetermined amount of air can be constantly supplied thereto.
An air pressure sensor (APS) is mainly used in order to measure an amount of air desirable for the gas boiler. In particular, such an air pressure sensor plays an important role of controlling an amount of the air required for the combustion of the gas boiler because the air pressure sensor applies an electrical signal to a main controller including a microcomputer by detecting a pressure of air.
However, conventionally, a breakage or an error of the air pressure sensor cannot be appropriately determined, and there is no method for quickly coping with the breakage or the error of the air pressure sensor.
In detail, in order to detect the breakage or the error of the air pressure sensor, the RPM of a fan is determined by means of a hall sensor provided in a predetermined portion of the fan during a combustion process of the gas boiler, and then, detection voltage of the air pressure sensor according to the RPM of the fan is compared with a preset value. If the detection voltage is beyond the range of the preset value, it is determined that the breakage or the error of the air pressure sensor occurs, so the combustion process of the boiler is stopped, and errors are displayed.
However, the RPM of the fan varies depending on an installation condition (for example, the length of the funnel) of the gas boiler, and, since the RPM of the fan may vary depending on external conditions thereof (such as, wind), the range of the RPM for determining the breakage of the air pressure sensor is expanded, so that it is difficult to exactly determine the breakage or the error of the air pressure sensor.
As a result, when the air pressure sensor is broken or fails, the optimum amount of air required for the combustion process is not supplied to the boiler, so unstable combustion of the boiler results. Accordingly, carbon monoxide (CO) may be excessively exhausted, or a status of a flame may be worsened.